Environmental Engineering Reference
In-Depth Information
Electronic
flashing light
5
1
Pressure resisitant
glass floats
Hollow rubber
ball depresses
lever(Ball
compresses and
releases at
30 to 45 ft)
Float
release
lever
Butterfly
valve
(open)
Wire
2
48 In.
4
80 In.
Plastic
core
liner
Plastic core
liner containing
sediment
Pilot weight
(down)
Stainless steel
core catcher
3
Core cutter
Ballast portion
(expendable)
Floats
released
Maximum depth
29,500 ft
Buttterfly
valve
(clossed by
released
floats
pilot weight (up)
FIGURE 2.74
The operating of sequence of the
Boomerang Corer. (From USACE 1996,
Pub. EM1110-1-1906. With permission.)
Benthos boomerang corer (model 1890)
Loss in caverns, large cavities, or highly fractured zones. In Figure 2.76, a light
drilling mud is being used to minimize fluid loss (note the mud “pit”), while cor-
ing in limestone with highly fractured zones above the water table.
When the prescribed coring length is obtained the core barrel is retrieved from the
ground. The core is removed from the barrel (Figure 2.77) and laid out in wooden boxes
exactly as recovered ( Figure 2.78) . Wooden spacers are placed to divide each run. The
depths are noted, the core is examined, and a detailed log is prepared.
Core Barrels
The selection of a core barrel is based on the condition of the rock to be cored and the
amount and quality of core required. Core barrels vary in length from 2 to 20 ft, with 5 and
10 ft being the most common.
Table 2.18 provides summary descriptions of suitable rock conditions for optimum
application, descriptions of barrel operation, and general comments. The types include:
Single-tube core barrel ( Figure 2.79) .
Double-tube rigid core barrel ( Figure 2.80 ).
Swivel-type double-tube core barrel, of two types: conventional and Series M
( Figure 2.81) . These types usually provide the best core recovery and are the
most commonly specified for rock coring.
Wireline core barrel ( Figure 2.82) .
 
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